Hybrid propulsion system for a motor vehicle

ABSTRACT

Arrangement for providing an integrated starter generator apparatus for producing electrical power and/or rotational torque. The apparatus includes a primary rotor ( 18 ) arranged for cooperation with a primary stator ( 16 ), and a secondary rotor ( 20 ) arranged for cooperation with a secondary stator ( 17 ). A one-way clutch ( 19 ) is disposed between the primary rotor ( 18 ) and the secondary rotor ( 20 ) that permits both rotors to be locked together in one direction of rotation, and that allows them to operate independently in the opposite direction of rotation.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation patent application ofInternational Application No. PCT/SE01/02072 filed 25 Sep. 2001 whichwas published in English pursuant to Article 21(2) of the PatentCooperation Treaty and which claims priority to Swedish PatentApplication No. 0003572-5 filed 2 Oct. 2000. Both applications areexpressly incorporated herein by reference in their entireties.

BACKGROUND OF INVENTION TECHNICAL FIELD

[0002] The present invention relates to an integrated starter generatorapparatus for producing electrical power and/or rotational torque. Theapparatus includes a primary rotor arranged for cooperation with aprimary stator, and a secondary rotor arranged for cooperation with asecondary stator. The invention also relates to a propulsion system fora motor vehicle including the integrated starter generator apparatus.

BACKGROUND OF THE INVENTION

[0003] On a parallel hybrid road vehicle using an internal combustionengine (ICE) and, for example, an integrated starter generator (ISG), itcan be desirable to be able to disconnect the ICE from the ISG in orderto drive the vehicle using electrical power only. Thus, it must bepossible to stop the ICE, then drive using the ISG as a traction motor,and when needed to be able to restart the ICE and to reconnect powertransmission.

[0004] WO 99/22955 discloses a hybrid propulsion system for a motorvehicle provided with an integrated starter generator apparatus. Thisapparatus includes a single stator-rotor unit and two independentlycontrollable, axially arranged clutches.

[0005] This and other types of known integrated starter generatorapparatuses increase the length of the propulsion system, especiallywhen a large electrical power capacity is needed.

SUMMARY OF INVENTION

[0006] A need exists for an integrated starter generator apparatushaving a large electrical power capacity as well as being longitudinallycompact. To fulfill this objective, an integrated starter generatorapparatus configured according to the present invention is characterizedin that it includes a one-way clutch disposed between the primary rotorand the secondary rotor thereby permitting both rotors to be lockedtogether in one direction of rotation, but also allowing them to operateindependently in the opposite direction of rotation.

[0007] According to an advantageous embodiment of the invention, theclutch and the primary and secondary rotors are concentrically arrangedabout a common axis of rotation.

BRIEF DESCRIPTION OF DRAWINGS

[0008] The invention will be further described in the following, in anon-limiting way with reference to the accompanying drawings in which:

[0009]FIG. 1 is a cross-sectional view showing a propulsion systemconfigured according to the present invention;

[0010]FIG. 2 is an exploded perspective view of the propulsion system ofFIG. 1; and

[0011]FIG. 3 is a detailed exploded perspective view of the integratedstarter generator portion of the apparatus configured according to theinvention.

DETAILED DESCRIPTION

[0012] An integrated starter generator apparatus that is configuredaccording to the teachings of the present invention enables theautomatic connection and disconnection of the power transmission betweenan internal combustion engine and the alternative drive machine in ahybrid road vehicle.

[0013]FIGS. 1 and 2 show the major components of a preferred embodimentof the inventive apparatus and propulsion system. The output shaft 10 ofan internal combustion engine is connected via an integrated startergenerator apparatus and a clutch 13 to a gearbox 14.

[0014] A housing 15 comprises a primary stator 16 and a secondary stator17. A primary rotor 18 is adapted to be mounted on the shaft 10 forrotation inside the primary stator 16. The primary rotor 18 is providedwith a centrally arranged one-way clutch 19. A secondary rotor 20 isadapted to be mounted on the clutch 19 so that both rotors are lockedtogether in one direction of rotation and able to operate independentlyin the opposite direction of rotation. The secondary rotor 20 forms theattachment point for the clutch 13 that is used as a conventional clutchwhen selecting different gears in the gearbox 14 for driving atdifferent speeds.

[0015]FIG. 3 is an exploded view of the primary rotor 18 with one-wayclutch 19. The clutch 19 is mounted inside a cylindrical flywheel mass21 with a clutch core 22 riding on bearings 23 and the clutch assemblyis locked inside the flywheel by means a circlip 24.

[0016] As may be best appreciated in FIG. 1, the primary 16, 18 andsecondary 17, 20 rotor-stator pairs and the one-way clutch 19 areconcentrically arranged about a common rotary axis (shown as a dash-dotline in FIG. 2). In order to achieve the most compact width-wisedimension for the integrated starter generator, the primary andsecondary rotor-stator pairs and the one-way clutch are each relativelypositioned to be substantially radially aligned about the rotary axisthereby establishing a width-wise overlapped arrangement therebetween.Still further, the primary and secondary rotor-stator pairs and theone-way clutch each have a width that is substantially equal to a widthof the integrated starter generator. In this context, it should beappreciated that the term substantially is utilized to indicate that theseveral widths do not necessarily have to be exactly equal when sodescribed, but they should be so nearly equal that when in theoverlapped configuration, the total width of the assembly does not varygreatly from any one of the required constituent components.

[0017] Below is a description of the major basic modes for a hybridvehicle using the propulsion system configured according to theinvention; but there are, of course, other modes that are not expresslyincluded.

[0018] In an internal combustion engine (ICE) start mode, the internalcombustion engine can be started by energizing the primary integratedstarter generator (ISG) stator 16.

[0019] In a conventional ICE drive mode, when the ICE is running, theone-way roller clutch 19 locks the drive so that the engine flywheel andthe secondary ISG rotor 20 rotate together. This enables full electricalpower to be generated by the ISG.

[0020] In an electric Vehicle (EV) mode, the ICE can be stopped. Thesecondary ISG stator 17 can be energized and EV drive is enabled by thesecondary rotor. In this mode, the one-way roller clutch 19 unlocks,disconnecting the drive between the ICE and secondary ISG rotor 20. Thismode can also be used for a creep function in very dense or slow movingtraffic.

[0021] In a vehicle coasting mode, for instance when going downhill andthe throttle is released, the ICE will go to idle and the one-way clutchwill unlock and become a free-wheel. In this mode, the primary ISGcontinues to generate power at a low level, and the secondary ISG caneither be used as a retarder if the vehicle speed must be reduced, or asa means of recuperating some of the vehicle's energy.

[0022] In general, the invention provides the following functionality.Normally required flywheel effect is maintained even when the driveconnection is separated. Adequate mechanical support and location ismaintained for the ISG rotor when drive is disconnected.Coupling/decoupling can occur completely automatically.Coupling/decoupling device may be maintenance free. ICE restarts ispossible by energizing part of ISG stator without having any effect onthe electrical drive.

[0023] The invention is not limited to the above-described embodiments,but several modifications are possible within the scope of the followingclaims.

1. An integrated starter generator for producing electrical power and/or rotational torque comprising: a primary rotor arranged for cooperation with a primary stator, and a secondary rotor arranged for cooperation with a secondary stator; a one-way clutch disposed between the primary rotor and the secondary rotor, the one-way clutch configured to permit both rotors to be locked together in one direction of rotation and to allow both rotors to operate independently in the opposite direction of rotation; and both rotors configured to provide flywheel mass when connected to a drive engine.
 2. The integrated starter generator according to claim 1, wherein the clutch and the primary and secondary rotors are concentrically arranged about a common axis of rotation.
 3. The integrated starter generator according to claim 2, wherein one of both rotors is connectable to an output shaft of a drive engine.
 4. The integrated starter generator according to claim 1, wherein the other of both rotors is connectable to a vehicle transmission.
 5. An integrated starter generator adapted for installation in a hybrid vehicle and for alternatively generating electrical power from, and providing rotational drive torque to an incorporating hybrid vehicle, the integrated starter generator comprising: primary and secondary rotor-stator pairs connectable together for alternatively generating electrical power from, and providing rotational drive torque to an incorporating hybrid vehicle; a one-way clutch disposed between the rotor-stator pairs thereby causing co-rotation in one direction and permitting opposed rotation in the other direction; and the primary and secondary rotor-stator pairs and the one-way clutch being concentrically arranged about a common rotary axis.
 6. The integrated starter generator according to claim 5, further comprising: the primary and secondary rotor-stator pairs and the one-way clutch each having a width substantially equal to a width of the integrated starter generator.
 7. The integrated starter generator according to claim 5, further comprising: the primary and secondary rotor-stator pairs and the one-way clutch each substantially radially aligned thereby establishing a width-wise overlapped arrangement between the primary and secondary rotor-stator pairs and the one-way clutch.
 8. An integrated starter generator adapted for installation in a hybrid vehicle and for alternatively generating electrical power from, and providing rotational drive torque to an incorporating hybrid vehicle, the integrated starter generator comprising: primary and secondary rotor-stator pairs connectable together for alternatively generating electrical power from, and providing rotational drive torque to an incorporating hybrid vehicle; a one-way clutch disposed between the rotor-stator pairs thereby causing co-rotation in one direction and permitting opposed rotation in the other direction; and the primary and secondary rotor-stator pairs and the one-way clutch each having a width substantially equal to a width of the integrated starter generator.
 9. The integrated starter generator according to claim 8, further comprising: the primary and secondary rotor-stator pairs and the one-way clutch each substantially radially aligned thereby establishing a width-wise overlapped arrangement between the primary and secondary rotor-stator pairs and the one-way clutch.
 10. A propulsion system for a motor vehicle comprising: an internal combustion engine and a multi-gear transmission, wherein the engine and the transmission are interconnected via an integrated starter generator; a primary rotor arranged for cooperation with a primary stator, and a secondary rotor arranged for cooperation with a secondary stator; a one-way clutch disposed between the primary rotor and the secondary rotor, the one-way clutch configured to permit both rotors to be locked together in one direction of rotation and to allow both rotors to operate independently in the opposite direction of rotation; and both rotors configured to provide flywheel mass when connected to a drive engine. 